# Statistics » Pie chart

## What is a pie chart?

A pie chart is a schematic representation of data within a circle.

Below you can see an example.

The different parts are called *sectors*.

The sector 'walk' is light blue.

This sector has a sector angle of 20 : 100 × 360° = 72°.

## How do you draw a pie chart?

You first have to calculate the size of the angles.

You can calculate the size of the sector angles by using ratio tables or with the formula `sector angle` = `number` : `total` × 360°

*Example*

A number of pupils is asked what their favorite pet is.

The results are in the table below.

Cats | 74 |

Dogs | 34 |

Birds | 20 |

Fish | 15 |

Other | 7 |

Draw a pie chart for this data.

First we need to know how many pupils have been asked.

74 + 34 + 20 + 15 + 7 = 150 pupils.

Now we can calculate the sector angles.

With a ratio table:

number of pupils | 150 | 1 | 74 | 34 | 20 | 15 | 7 |

angle in degrees | 360 | 2.4 | 177.6 | 81.6 | 48 | 36 | 16.8 |

Or with the formula:

74 : 150 × 360° = | 177.6° |

34 : 150 × 360° = | 81.6° |

20 : 150 × 360° = | 48° |

15 : 150 × 360° = | 36° |

7 : 150 × 360° = | 16.8° |

Now you can draw the pie chart.

Did you forget how to draw or measure angles? Check angles.